1. Field of the Invention
The present invention relates to a toner supplying device used in an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, or the like, and particularly to a toner supplying device applied to an image forming apparatus so constituted that a developing device is positioned on a lower side and a toner supplying device is positioned on an upper side and that the developing device and the toner supplying device are spaced from each other in some degree.
2. Description of the Related Art
In a conventional image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, or the like, after a surface of a photoconductive drum was uniformly charged with the predetermined electric potential, it is exposed to light and an electrostatic latent image is formed. The electrostatic latent image formed on the surface of the photoconductive drum is made visible by a developing device, that is, it is formed as a toner image. The toner image is transferred/fixed onto a transfer sheet, whereby an image is formed.
In the above image forming apparatus, together with the operation of developing the electrostatic latent image formed on the surface of the photoconductive drum by the developing device, toner within the developing device is consumed. Therefore, a toner supplying device is provided in order to supply the toner to the developing device at the predetermined timing. This toner supplying device is usually constituted so that it is arranged on a side of the developing device, viewed from a front side of an image forming apparatus body and that the toner is supplied to the developing device by transporting the toner from the toner supplying device in the horizontal direction.
However, in the above image forming apparatus, as an image is made into a full color image, the apparatus is miniaturized, or the apparatus runs at a higher speed, recently, new apparatuses having various apparatus designs and layouts are being proposed and being produced.
In an image forming apparatus according to this new proposal, there is an image forming apparatus so constituted that a toner supplying device is spaced from a developing device in some degree and arranged at an upper portion within the image forming apparatus body, and that the developing device is positioned on the lower side and the toner supplying device is positioned on the upper side.
In case of this image forming apparatus so constituted that the developing device is positioned on the lower side and the toner supplying device is positioned on the upper side, and that the developing device and the toner supplying device are spaced from each other in some degree, a transporting passage A that determines the supplied amount of the toner from the toner supplying device and a transporting passage B for supplying the toner transported along the transporting passage A to the developing device are required. Since the transporting passage A determines the amount of the toner supplied from the toner supplying device, a transporting member such as an auger is disposed inside the transporting passage A, and the above transporting passage A is disposed in a substantially horizontal direction. On the other hand, the transporting passage B is disposed in a substantially vertical direction in order to connect the toner supplying device positioned on the upper side to the developing device positioned on the lower side.
As a means for transporting toner in the substantially vertical direction within the transporting passage B connecting the toner supplying device positioned on the upper side to the developing device position on the lower side as described above, there are the following means.
(1) A means so constituted that, as shown in FIG. 14, toner is supplied from a toner supplying device 100 into a first transporting passage 101 disposed in the substantially horizontal direction, that the toner is transported into the first transporting passage 101 by an auger 102 in the horizontal direction and then transported from the first transporting passage 101 into a second transporting passage 103, and that the toner supplied into this second transporting passage 103 is transported according to its natural dropping thereby to be transported to a developing device 104.
(2) A means so constituted that, as shown in FIG. 15, a spring agitator 106 is disposed inside a second transporting passage 103, that an end portion of this spring agitator 106 is directly connected to an auger 102 disposed inside a first transporting passage 101, that the first transporting passage 101 and the second transporting passage 103 are curved with a predetermined curvature radius to be coupled to each other, and that the toner supplied into the second transporting passage 103 is transported to a developing device 104 by the spring agitator 106.
(3) A means so constituted that, as shown in FIG. 16, transporting members 102 and 107 each of which is composed of an individual auger are disposed inside a first transporting passage 101 and a second transporting passage 103, that power is transmitted form a shaft of the transporting member 102 disposed inside the first transporting passage 101 through gears 108, 109 such as a bevel gear, a helical gear or the like to the transporting member 107 such as the auger disposed inside the second transporting passage 103 composed of the auger, and that the toner supplied into the second transporting passage 103 is transported to a developing device 104 by this transporting member 107.
However, the following problems exist in the above conventional arts.
(1) In case that the toner supplied into the second transporting passage 103 is transported according to its natural dropping as shown in FIG. 14, there is a problem that possibility of clogging of the second transporting passage 103 with the toner is large by some size of a diameter or a length of the second transporting passage 103 and by quality of some toner. In order to solve this problem, there is an apparatus so constituted that vibration is applied to the second transporting passage 103. However, in this case, the number of parts increases, which causes an increase in cost and makes the apparatus larger.
(2) In case that the first transporting passage 101 and the second transporting passage 103 are curved with the predetermined curvature radius to be coupled to each other as shown in FIG. 15 and that the toner supplied into the second transporting passage 103 is transported by the spring agitator 106, a large curvature radius must be set at a portion for coupling the first transporting passage 101 and the second transporting passage 103 to each other, which is unadaptable on layout. Further, since the spring agitator 106 is disposed inside the second transporting passage 103 is curved and rotated, it is strongly pressed against a wall surface of the second transporting passage 103, so that there is fear that stress will be given to the toner that is transported inside the second the transporting passage 103, and that a bad influence will be exerted on the toner.
(3) In case that the transporting members 102 and 107 each of which is composed of the individual auger are disposed inside the first transporting passage 101 and the second transporting passage 103 as shown in FIG. 16, and that the power is transmitted from the transporting member 102 disposed inside the first transporting passage 101 through the gears 108, 109 such as the bevel gear, the helical gear or the like to the transporting member 107 disposed inside the second transporting passage 103, there is no problem on transportability of toner but there is a problem that the number of parts such as the gears 108, 109 increases and the increase in cost is caused.
Therefore, the invention has been made in order to solve the problems of the above conventional arts. Its object is to provide a toner supplying device, which has such a constitution that a developing device is positioned on a lower side, the toner supplying device is positioned on an upper side, and their devices are spaced from each other in some degree; which makes large the freedom of the layout of a transporting passage along which toner is transported from the toner supplying device to the developing device without causing an increase in cost caused by the increase of the number of parts and making the apparatus larger; and which has no fear that stress will be given to the toner transported along the transporting passage and a bad influence will be exerted on the toner.
In order to solve the above problems, according to a first aspect of the invention, in a toner supplying device in which a developing device to which toner is to be supplied is arranged on a lower side and a toner supplying device is arranged on an upper side, and the toner is supplied through a first transporting passage disposed in a substantially horizontal direction and a second transporting passage disposed in a substantially vertical direction; the toner supplying device is so constituted that a transporting member for transporting the toner by its rotation is provided inside the first transporting passage, and that a transporting member provided inside the second transporting passage is moved in the vertical direction through a converter for converting the rotation of the transporting member provided inside the first transporting passage into reciprocation.
Further, according to a second aspect of the invention, the toner supplying device is, in the first aspect, characterized in that the converter for converting the rotation of the transporting member provided inside the first transporting passage into the reciprocation is composed of a crank-shaped shaft provided for the transporting member disposed inside the first transporting passage.
Further, according to a third aspect of the invention, the toner supplying device is, in the first aspect, characterized in that the converter for converting the rotation of the transporting member provided inside the first transporting passage into the reciprocation is composed of an eccentric cam provided for the transporting member disposed inside the first transporting passage.